add None check
add None check

hvy/chainer,okuta/chainer,okuta/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,chainer/chainer,hvy/chainer,niboshi/chainer,niboshi/chainer,pfnet/chainer,wkentaro/chainer,jnishi/chainer,hvy/chainer,hvy/chainer,niboshi/chainer,wkentaro/chainer,jnishi/chainer,niboshi/chainer,ktnyt/chainer,jnishi/chainer,wkentaro/chainer,okuta/chainer,keisuke-umezawa/chainer,tkerola/chainer,chainer/chainer,ktnyt/chainer,ktnyt/chainer,ktnyt/chainer,jnishi/chainer,chainer/chainer,wkentaro/chainer,chainer/chainer,okuta/chainer,keisuke-umezawa/chainer